Selective IgA deficiency — MRCPCH TAS MCQ

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EasyImmunologySelective IgA deficiencyMRCPCH TAS

A 6-year-old has recurrent sinus infections and diarrhoea. Immunology shows undetectable IgA with normal IgG and IgM. What is the most likely diagnosis?

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Correct answer: D — Selective IgA deficiency

Selective IgA deficiency causes low or absent IgA with preserved IgG and IgM and may present with mucosal infections or be asymptomatic. X-linked agammaglobulinaemia would show very low levels of multiple immunoglobulin classes and absent B cells. The pearl is that IgA deficiency can coexist with atopy or autoimmune disease.

Reference: Nelson Textbook of Pediatrics; RCPCH Theory examination syllabi; Lissauer's Illustrated Textbook of Paediatrics